Draft controller



A. M, WILKINS DRAFT, CONTROLLER Mar ch 7, 1933.

Filed Jan. 16, 1931 Patented Mar. 7, 1933 UNITED STATES PATENT OFF-ICE I ALBERT M. wILKms," or 'cHIcAGo, ILLINOIS, ASSIGNOR T0 coox ELECTRIC 0011mm} orcHIcAGo, ILLINOIS, a CORPORATION or ILLINOIS I DRAFT CONTROLLER My invention relates to electric draft c.0ntrollers for heating systems designed to operate by any form of electrical meansand controlled automatically byws'uitable means,

.1? which may be thermostatically or otherwise.

In the operation of heating-systems pro vided with automatically-controlled electrlc draft controllers, independent control at the furnace of the draft and check dampers is- I 9 desirable, so that during the. firing of the furnace at least the checkdamper,-if-not both dampers, may be closed. After the firing'of operate to open and close the check and draft dampers'under the control of a thermostat or the like, but which-will permit independent control of the dampers'at the furnace for the purpose of being closed, when the furnace is fired and the fire door is opened, and which will resume automatic control over the dampers when the fire door is closed.

A further object of my invention is to pro,- vide a manually operated member adjacent to the fire door of the furnace,which, when moved manually, will close the check and draft dampers and permit the fire door of the furnace to be opened.

Specifically, these results are accomplished V by allowing the damper doors to drop; to

closed position by the slack provided in the flexible connections, between the damper doors and the damper actuating arm of the controller,- whenthe fire door is opened to fire the furnace. Closing of'the fire door after the, firing operation will take up, the slack so .that the damper doors will thereby be set in their normal position for continued automatic control by the draft controller. I

I am aware that it is customary to make provision forclosing the draft door or damper during firing of the furnace. 3

My invention, however, 1s fundamentally different in that the independent control over' the draft door during firing is not obtained by temporarily disconnecting the controlof the motor of the draft controllerfrom the damper actuating arm; in fact, the independent control has no relation to the operation of the draft controller, inasmuch as the draft controller may continue to operate un der the influence of the room thermostat, thereby obviatingany possibility of failingto resume control over the damper doors through failure of the disconnecting means to function properly. p I v In order to apprise those skilled in the art how to construct and practice my invention, I shall now describe a preferred embodiment thereof in connection with the accompanying drawing, inwhich:

Figurel is a view illustrating the front portionof a furnace or heater with the struc- Eure embody-ingmy inventionapplied there- Fig. 2 is an elevation of one side of the con- 'troller Withthe side of the cover removed;

and, r Fig. 3 is a view of the rear wall of the controller illustrating certain circuit connections.

My invention, as embodied in the structure shownin the drawing,- comprises an electric draft. controller 1 which may be applied to various types ofv heaters or furnaces having the usual draft orair inlet 2 and-a check damper 3. I

In the drawing, I have illustrated a furnace, being designated 4;, but it will be understood thatin so far as the disclosure of my invention is concerned, the illustration is merely conventional, inasmuch as the invention is capable of wide application in this field and may be used to control elements other thanthe dampers ofheaters.

The electric draft controller 1 is provided with-a damper lever 5, mounted preferably in pivotal relation at the bottom of the controller, and having the ends of its arms perforated to permit attachment of suitable connections to the da'mpers'Q and 3. The lefthand arm of; damper lever 5 may be connected to checkdamper 3 by a chain or other suitable connection 6, while the right-hand arm of damper lever 5 may be connected to draft or air. inlet. damper 2 by a chain or other suitable connection 7. Movement of damper lever 5 clockwise raises the left-hand arm to close check damper 3 and lowers the righthand arm to open air inlet damper 2. Counterclockwise movement of damper lever 5 to the extreme opposite position closes air inlet damper 2 and opens check damper 3.

The particular illustration of the use to which my invention has been put may obviously be varied, including the relative arrangement or construction of the lever arms with respect to each other, without altering the operation of the controller or the flexible connections 6 and 7, to be presently described.

Any suitable actuating means may be provided as part of the electric draft controller for operating damper lever 5. It will be understood that while thermally operated element or vapor motor 9 is illustrated, any suitable electrical mechanism or motor may be used instead in connection with the invention disclosed herein.

Thermal element 9 may comprise a rigid outer Wall 10 and an expansible and contractible inner. wall 14, suitably sealed together in hermetical relation at the lower end andfastened to base 12 of the housing of the controller. A tube 16, provided with a heat coil 11, is closed at its top and communicates with the interior of a closed chamber provided by outer and inner walls 10 and 14. An actuating arm 17 extends through base 12 and into inner wall 14, being operably' connected to the top of the inner wall.

A controller housing includes a vertical wall plate 21 carrying any suitable form of transformer 22, if so desired, and thermal blocks 23 and 24. Primary coil of transformer 22 is adapted to receive line wires 25 and 26, which wires are continued at 29 and 30, from the secondary coil of transformer 22 to terminal block 23. Wire 31, compris ing a continuation of the circuit from wire 30 through terminal block 23, may connect to a terminal band 32 (Fig. 2) surrounding and suitably attached at the upper end of tube 16. Heat coil 11 may be attached at its upper end to terminal band 32'. Wire 33 of the opposite side of secondary coil of transformer 22 forming a continuation ofthe circuit by electrically connecting to wire 29' at terminal block 23, connects to a terminal 35, on terminal block 24, and by means of a wire 38, to a thermostat-39. This thermostatic circuit is ing andsuitably attached at the lower end of tube 16.

Y The closed chamber defined by the space between outer wall 10 and inner wall 14, as

well as the interior of tube 16, is adapted to contain a volatile fluid, which, when heated, will develop a pressure to move operating arm 17 downwardly. Such movement operates damper lever 5 clockwise, whereby to open draft or inlet damper2 and to close check damper 3. This action normally occurs when the heating circuit is closed by the closing of roomthermostat 39 upon lowering of the temperature in the room.

The volatile fluid will be heated by current flowing through heat coil 11 to develop heat at tube 16. The'heat vaporizes and drives the volatile substance into the closed chamber of thermal element 9, whereby to expand the chamber and move actuating arm 17 downwardly; Coil 11 about tube 16 forms or establishes a heating zone. When the volatile substance is drivenoutof this heating zone into the closed chamber, further expansion thereof is checked. This movement of actuating arm 17 pivots damper lever 5 in a clockwise direction, as shown in Fig. 3, to open air inlet 2 and to close check damper 3. Air supplied to heater 4 by way of air inlet damper 2 supports combustion in the heater whereby the room temperature will rise and room thermostat'39 will open. Tube 16 then cools and the vapor condenses to allow the volatile substance to return into tube 16. The closed chamber will return to normal position and the upward movement of actuating arm 17 will rotate damper lever 5 counterclockwise whereby air inlet damper 2 is closed and check damper 3 is open.

During the'firing of furnace 4, it may be desirable to close one or both dampers and check the draft. Temporarily disconnecting chains 6 and 7 to accomplish this result should not be permitted because it is possible that the attendant will forget to reconnect these chains to restore automatic control.

' ll provide means for closing either or both of damper doors 2 and 3 upon opening of the fire door 40. The arrangement includes a manually operated handle 41 suitably pivoted at 42 on heater 4 adjacent to door 40 to permit one end of this handle to overlie door 40, when in horizontal position, whereby to hold door 40 closed. At any suitable point, but preferably vertically thereover, a bracket 43 may be attached to a mouting 44. The horizontal leg of bracket 43 has openings therein to allow vertical movement of pins 45. Pins 45 are fixed to a horizontal bar 47 carrying pulleys 48 and 49 adjacent to its ends. Chains 6 and 7 may be entrained over pulleys 48 and 49, respectively. Vertical movement of horizontal bar 47, being guided in such movement by pins 45, is provided by movement of a chain 50 connecting at its opposite end to fire door handle 41. Chain 50 may be supported in overhead relation by suitable guide pulleys 51 and 52. Moving handle 41 to the postion shown in Fig. 1 allows bar 47 to drop a short distance, thereby lowering pulleys 48 and 49. Lowering the pulleys 48 and 49 places slack in chains 6 and 7 so as to allow doors 2 and 3 to close, it being under stood that it is common practice in the art to support such doors on a horizontal axis so that they close by their own weight.

When handle 41 is moved to a horizontal position so that the right-hand end of the handle engages fire door 40 to prevent it from being opened, the bar 41 is raised to take up the slack in chains 6 and 7 Draft or air" inlet damper 2 and check damper 3 are again placed in their former position and automatic control by draft controller 1 over these dampers is again resumed.

From the foregoing description, it will be obvious that a very simple form of draft con the chains shown in the drawing is simple,

inexpensive and positive in operation.

Without further elaboration, the foregoing will so fully explain the gist of my invention, that others may, by applying current knowledge, readily adopt the same for use under varying conditions of service, without eliminating certain features, which may' properly be said to constitute the essential items of novelty involved, which items are intended to be defined and secured to me by the following claims.

I claim:

1. An automatic control for operating the draft damper and check damper of a furnace comprising, in combination, a motor, a thermostat responsive to temperature variations for controlling the operation of the motor, a damper actuating member adapted to be operated by the motor to control thedampers, flexible connections between the damper actuating member and the dampers, a support mounted substantially above the motor and the dampers, a member mounted for reciprocal movement in said support, pulleys upon the reciprocal member over which the flexible connections extend from the dampers to the damper actuating member, and a flexible con nection for holding the reciprocal member in the support adapted to raise and lower the pulleys on said bar, pins on said bar movable in the apertures of the U-bracket, a flexible connection holding the pins in the apertures, other flexible connections extending over the pulleys from the dampers to the damper controller, and a connection between the first said flexible connection and the fire door of the furnace whereby opening of the fire door causes the first said flexible connection to lower the pins in the apertures whereby to lower the bar and temporarily to disconnect the dampers from the control of the damper controller.

3. An automatic control for operating the draft damper and check damper of a furnace comprising, in combination, a motor, a thermostat responsive to temperature variations for controlling the operation of the motor, a damper actuating member adapted to be operated'by the motor to control the dampers,

flexible, connections between the damper actuating member and the dampers, a support mounted substantially above the motor and the dampers, a member mounted for reciprocal movement in said support, pulleys upon the reciprocal member over which the flexible connections extend from the dampers to the damper actuating member, and a flexible connection for holding the reciprocal member in the support adapted to raise and lower the same.

4. An automatic control for operating one .or more dampers of a furnace comprising, in

combination, a support mounted substantially above said dampers, a member mounted for reciprocal movement in said support, connections leading to said dampers from said reciprocal member, and means for raising and lowering said reciprocal memberin said support to open and close said dampers.

In witness whereof, I have hereunto subscribed myname.

ALBERT M. WILKINS.

same depending upon the, position of the fire door of the furnace.

2. An automatic control for operating the draft damper and the check damper of a furnace comprising, incombination, a damper controller, a thermostat for controlling the operation of the damper controller, an apertured U-bracket rigidly supported above the dampers and the damper controller, a bar, 

